A team of marine ecologists from Oregon State University described the formation and development of a new methane leak, a place where methane escapes from an underground reservoir into the ocean, in the Ross Sea, Upper Antarctica.
Cinder’s cones leak, Ross Sea, Antarctica: White microbial mats are telltale signs of areas where methane can be released from underground methane deposits. Image credit: Andrew Thurber, Oregon State University.
“Methane is the second most effective gas to heat our atmosphere and Antarctica has large reserves that are likely to open up as ice sheets retreat due to climate change,” said Dr. Andrew Thurber, a marine ecologist at the Faculty. of Earth and Department of Microbiology of Oregon State University.
“This is a significant discovery that can help fill a huge gap in our understanding of the methane cycle.”
Methane is a greenhouse gas that is 25 times more powerful than carbon dioxide to heat the planet.
Most of the methane in ocean water and sediment is kept out of the atmosphere by the microbes that consume it.
In 2011, an expansive microbial mat (70m by 1m, or 230ft by 3.3ft) was formed 10m (33ft) deep at the Cinder Cones site at McMurdo Sound within the Ross Sea.
“Leakage from cinder cones was discovered in an area that scientists have studied for over 60 years, but the leak was not active until 2011,” said Dr. Thurber.
He and his colleagues discovered that the microbes around this leak are fundamentally different from those found elsewhere in the world’s oceans.
“These mats, which are produced by bacteria that exist in a symbiotic relationship with methane users, are a telltale indication of the presence of a leak,” he explained.
“The microbial mat is the road sign that there is a methane leak here. We don’t know what caused these leaks to trigger. We needed a little luck to find an active one, and we did it. ”
“Antarctica is believed to contain up to 25% of Earth’s marine methane. Having an active filtration to study gives us a new understanding of the methane cycle and how that process might differ in Antarctica compared to other places on the planet. “
For example, the researchers found that the most common type of methane-consuming microbe took five years to appear at the filtration site, and even then those microbes were not consuming all of the methane.
That means that some methane is being released and is likely reaching the atmosphere.
“Studying the site over a five-year period allowed us to see how microbes respond to the formation of a leak,” said Dr. Sarah Seabrook, who earned her doctorate from Oregon State University and is now a postdoctoral researcher in New Zealand. National Institute of Water and Atmospheric Research.
“What was really interesting and exciting was that the microbial community did not develop as we would have predicted based on other methane leaks that we have studied around the world.”
“We assumed that microbes should respond really quickly to changes in the environment, but that was not reflected in what we saw in Antarctica,” said Dr. Thurber.
“To add to the mystery of Antarctic leaks, the microbes we found were the ones we least expected to see here.”
“There may be a pattern of succession for microbes, with certain groups coming first and those that are most effective at eating methane come later.”
The team’s article was published in the Proceedings of the Royal Society B.
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Andrew R. Thurber et al. Riddles in the cold: Antarctic endemism and microbial succession impact the methane cycle in the Southern Ocean. Proc. R. Soc. Yes 287 (1931): 20201134; doi: 10.1098 / rspb.2020.1134
